Device for transporting thermal energy at temperatures lying below the {80 -temperature of helium

ABSTRACT

A device for transporting thermal energy at temperatures lying below the lambda -temperature of helium between a cooled 4He container having a temperature lower than that of the lambda point and a place to be cooled or a further container; the device comprises a pipe which has one end in communication with said container and the other end which is brought in thermal contact with the article to be cooled or debouches in the further container, the pipe comprising a sintered superleak which extends throughout the length of the pipe and covers a part of the crosssection thereof.

United States Patent 1151 3,678,704 Staas 1451 July 25, 1972 s41 DEVICE FOR TRANSPORTING 3,195,322 7/l965 London ..62/5l4 THERMAL ENERGY AT 3,376,712 4/1968 London ...62/5 14 TEMPERATURES LYING BELOW THE 3,447,333 6/1969 Goodstein..... ...62/5 14 )TEMPERATURE OF HELIUM 3,581,512 6/l97l Stzas et a] ..62/5 14 [72] Inventor: Frans Adrianus Staas, Emmasingel, Eind- P i E i -M Perlin hove", Netherlands Attorney-Frank R. Trifari [73] Assi nee: U.S. Philips Corporation New York, NY.

g 57 ABSTRACT [22] Filed: Oct. 13, 1970 A device for transporting thermal energy at temperatures [21] Appl' lying below the A -temperature of helium between a cooled He container having a temperature lower than that of the A [30] Foreign Application Priority Dltl point and a place to be cooled or a further container; the device comprises a pipe which has one end in communication Oct. 16, 1969 Netherlands ..69l 5652 with said container and the other end which is brought in then 52 us. c1 ..62/5l4 with article be debwches [5] 1 Int. Cl l F25b19/00 further container, the pipe comprising a sintered superleak 58 Field of Search ..62/5l4, 515 which extends throughout the length of the p p and covers a part of the cross-section thereof. [56] References Cited 2 Claim, 1 Drawing Figure UNITED STATES PATENTS 2,350,348 6/1944 Gaugler ..62/5l5 Patented July 25, 1972 3,678,704

[\WENTOR.

FRANS A. STAAS AGENT TEMPERATURE LYING BELOW THE [-TEMPERATURE OF I-IELIUM BACKGROUND OF THE INVENTION The invention relates to a device for transporting thermal energy at temperatures lying below the lt-temperature of helium between a cooled He container having a temperature lower than that of the )t-point and a place to be cooled or a further container; the device comprises a pipe which has one end in communication with said container and the other end of which can be brought in thermal contact with the object to be cooled or debouches in the further container.

It is known that He at temperatures below the A-point has a thermal conductivity which is very much (1,000 X) larger than that of solids. This property can be related to the fact that He at these temperatures consists in part of normal fluid which is viscous and has a given entropy, while the other part is a superfluid which has no viscosity and an entropy zero. When thermal energy is supplied to one end of the pipe by the object to be cooled, a temperature difference A T occurs across said pipe in which a thennal transport starts occurring in that superfluid starts flowing toward the warmer end, while normal fluid flows in the opposite direction, and that in such manner that the overall mass transport is zero. It has been found that the so-called reciprocal friction of the flow of superfluid and the oppositely directed flow of normal fluid, particularly in the case of a larger supply of thermal energy, has a very adverse influence on the quantitity of thermal energy which can be transported.

SUMMARY OF THE NEW INVENTION It is the object of the invention to provide a device of the type to which the present invention relates and which has a better power of transporting thermal energy than the so far known devices.

In order to achieve this objective the device according to the invention is characterized in that the pipe comprises a sin tered superleak which extends throughout the length of the pipe and covers a part of the cross-section of the pipe.

Within the scope of the present application, a superleak is to be understood to mean a mass of material of such a high density that normal fluid cannot pass through said mass and superfluid can pass through said mass without turbulence in the fluid.

If in the device according to the invention, a temperature difference A T is applied across the pipe, the superfluid will flow through the superleak to the place of higher temperature, while the normal fluid will flow in the opposite direction through the remainder of the tube. The so-called reciprocal friction between the two flows does not occur, which results in a considerably better thermal conductivity and hence in a lower temperature difference A T with the same thermal flow.

In a further favorable embodiment the superleak covers the whole inner wall of the pipe. The advantage of this is that the superleak also counteracts penetration of thermal energy from without.

BRIEF DESCRIPTION OF THE DRAWING In order that the invention may be readily carried into effect, it will now be described in greater detail, by way of example, with reference to the accompanying drawing showing an embodiment of a device for transporting thermal energy and consisting of a pipe with He and provided with a superleak.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference numeral 1 denotes a container filled with liquid He at a temperature lower than that of the A-point. pipe 2 communicates with the said container and communicates at its other end 3 in a heat conducting manner with an object 4 to be cooled. The inner wall of the pipe 2 is covered with a superleak 5 of, for example, sintered aluminum oxide particles or silicon carbide particles. Such a superleak has the property that normal fluid cannot pass through it, while superfluid flows through such a superleak without turbulence occurring. When thermal energy is supplied to the end of the tub 3 by the article 4, a certain temperature difference occurs across the pipe 2. The superfluid will start flowing to the end 3 of the pipe while an equally large mass flow of normal fluid will flow to container l. The superfluid will flow through the superleak 5 without turbulence, so that the flow of normal fluid is not impeded. In this manner, a particularly large amount of thermal energy can be transported through pipe 2, with a small temperature difference across the pipe.

Providing the superleak against the inner wall of the tube 2 has the advantage that the superleak. counteracts inleak of thermal energy but, if desirable, the superleak may also be arranged detached from the wall of the pipe.

Instead of bringing the end 3 of the pipe in thermal contact with an object to be cooled, the pipe may also be made to communicate with a further container which, for example, serves as a storage container from which liquid can be drained or which is in thermal contact with a number of objects to be cooled.

What is claimed is:

l. A device for transporting thermal energy at temperatures lying below the )t-temperature of helium, between a container of cooled l Ie having a temperature lower than that of the A- point and an object to be cooled, the device comprising a pipe which has one end in communication with said container, and the other end which can be brought into thermal contact with the object to be cooled, characterized in that said pipe comprises a sintered superleak which extends along the length of said pipe and extends across only a part of the cross-section thereof.

2. A device as claimed in claim 1, characterized in that the superleak covers the whole inner wall surface of the pipe. 

1. A device for transporting thermal energy at temperatures lying below the lambda -temperature of helium, between a container of cooled 4He having a temperature lower than that of the lambda -point and an object to be cooled, the device comprising a pipe which has one end in communication with said container, and the other end which can be brought into thermal contact with the object to be cooled, characterized in that said pipe comprises a sintered superleak which extends along the length of said pipe and extends across only a part of the crosssection thereof.
 2. A device as claimed in claim 1, characterized in that the superleak covers the whole inner wall surface of the pipe. 